:root {
  --bg: #f5f3eb;
  --surface: #fffdf8;
  --surface-strong: #efe7d7;
  --ink: #1f2733;
  --muted: #586271;
  --line: rgba(31, 39, 51, 0.12);
  --accent: #124170;
  --accent-soft: #d6e4f3;
  --accent-warm: #c96d33;
  --shadow: 0 18px 40px rgba(24, 32, 44, 0.08);
  --radius: 24px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Avenir Next", "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(201, 109, 51, 0.12), transparent 28%),
    linear-gradient(180deg, #fbf8f2 0%, var(--bg) 48%, #f0eee8 100%);
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.wrap {
  width: min(1160px, calc(100% - 2rem));
  margin: 0 auto;
}

.site-header {
  padding: 1.1rem 0 2.5rem;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 2.2rem;
}

.brand {
  font-size: 0.95rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink);
}

.topnav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 0.7rem;
}

.pill-link,
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0.7rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 253, 248, 0.9);
  color: var(--ink);
  font-weight: 700;
}

.button {
  padding-inline: 1.15rem;
}

.button:hover,
.pill-link:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

.button-primary {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.button-secondary {
  background: transparent;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(280px, 0.85fr);
  gap: 1.4rem;
  align-items: stretch;
}

.hero-copy,
.hero-panel {
  background: rgba(255, 253, 248, 0.84);
  border: 1px solid rgba(18, 65, 112, 0.12);
  border-radius: 30px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(8px);
}

.hero-copy {
  padding: 2rem;
}

.eyebrow,
.section-kicker {
  display: inline-block;
  margin-bottom: 0.8rem;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-warm);
}

.hero h1,
.section-heading h2 {
  margin: 0;
  line-height: 1.05;
  font-family: Georgia, "Times New Roman", serif;
  letter-spacing: -0.02em;
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4.8rem);
}

.hero-text,
.section-heading p,
.resource-card p,
.lecture-body p,
.exercise-note,
.exercise-empty p,
.exercise-set-description {
  color: var(--muted);
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin-top: 1.6rem;
}

.hero-panel {
  padding: 1.35rem;
}

.hero-panel-goals {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-goals {
  display: grid;
  gap: 0.95rem;
}

.hero-goals p,
.section-lead,
.lecture-meta {
  margin: 0;
  font-size: 0.92rem;
  color: var(--muted);
  line-height: 1.7;
}

.lecture-meta-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.1rem;
  flex-wrap: nowrap;
}

.section {
  padding: 1.2rem 0 4rem;
}

.section-alt {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.35), rgba(234, 229, 220, 0.55));
  border-block: 1px solid rgba(18, 65, 112, 0.08);
}

.section-heading {
  max-width: 760px;
  margin-bottom: 1.7rem;
}

.section-heading h2 {
  font-size: clamp(1.9rem, 4vw, 3rem);
}

.lecture-grid,
.resource-grid {
  display: grid;
  gap: 1rem;
}

.resource-card,
.lecture-card,
.exercise-list button,
.exercise-panel,
.exercise-note {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.resource-card,
.exercise-note {
  padding: 1.4rem;
}

.lecture-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.lecture-card {
  overflow: hidden;
}

.lecture-card-featured {
  grid-column: span 3;
  display: grid;
  grid-template-columns: minmax(420px, 560px) minmax(0, 1fr);
  align-items: stretch;
}

.lecture-poster {
  min-height: 136px;
  display: flex;
  align-items: flex-end;
  justify-content: flex-start;
  padding: 0.9rem;
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: white;
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

.lecture-poster span {
  display: inline-flex;
  padding: 0.28rem 0.62rem;
  border-radius: 999px;
  background: rgba(255, 253, 248, 0.2);
  backdrop-filter: blur(4px);
}

.lecture-poster-intro {
  background: linear-gradient(135deg, #124170 0%, #2d6e9a 100%);
}

.lecture-poster-intro-hall {
  min-height: 0;
  height: 100%;
  aspect-ratio: 16 / 10;
  background:
    linear-gradient(135deg, rgba(26, 36, 52, 0.38), rgba(141, 77, 39, 0.34)),
    url("./assets/praesenz-hoersaal.jpg");
  background-position: center center;
}

.lecture-poster-online {
  min-height: 156px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    #ffffff;
  background-position: center 44%;
  background-size: 118% auto;
  background-color: #dfe4eb;
}

.lecture-poster-online span {
  color: #ffffff;
  background: rgba(35, 49, 66, 0.86);
}

.lecture-poster-finanzmathematik {
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    url("./assets/thumb-finanzmathematik.png");
}

.lecture-poster-sicherheit {
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    url("./assets/thumb-sicherheit.png");
}

.lecture-poster-steuern {
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    url("./assets/thumb-steuern.png");
}

.lecture-poster-fisher {
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    url("./assets/thumb-fisher.png");
}

.lecture-poster-unsicherheit {
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    url("./assets/thumb-unsicherheit.png");
}

.lecture-poster-finanzinstrumente {
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(30, 44, 60, 0.04)),
    url("./assets/thumb-finanzinstrumente.png");
}

.lecture-poster-presence {
  min-height: 220px;
  background:
    linear-gradient(135deg, rgba(26, 36, 52, 0.38), rgba(141, 77, 39, 0.34)),
    url("./assets/praesenz-hoersaal.jpg");
  background-position: center center;
  background-repeat: no-repeat;
  background-size: cover;
}

.lecture-body {
  padding: 1.2rem 1.2rem 1.3rem;
}

.lecture-poster-link {
  display: block;
  margin: 0.9rem 0 0.95rem;
  border-radius: calc(var(--radius) - 10px);
  overflow: hidden;
  text-decoration: none;
}

.lecture-body h3,
.resource-card h3,
.exercise-empty h3,
.exercise-header h3,
.question-card h4 {
  margin: 0;
  font-size: 1.15rem;
}

.imprint-box {
  background: #fbfbfc;
}

.imprint-box p {
  margin-top: 0;
  margin-bottom: 12px;
}

.imprint-box p:last-child {
  margin-bottom: 0;
}

.lecture-meta {
  margin: 0 0 0.45rem;
  color: var(--accent-warm);
  font-weight: 700;
}

.lecture-submeta {
  margin: -0.1rem 0 0.6rem;
  font-size: 0.92rem;
  color: var(--muted);
}

.lecture-submeta a {
  font-weight: 600;
}

.link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1rem;
}

.link-row a {
  font-weight: 700;
}

.link-row .login-note {
  font-weight: 400;
  color: var(--muted);
}

.lecture-duration {
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 400;
  line-height: 1.4;
  white-space: nowrap;
  flex: 0 0 auto;
  text-align: right;
}

.exercise-intro {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-bottom: 1.3rem;
}

.exercise-layout {
  display: grid;
  grid-template-columns: minmax(260px, 320px) minmax(0, 1fr);
  gap: 1rem;
  align-items: start;
}

.exercise-list {
  display: grid;
  gap: 0.85rem;
}

.exercise-list button {
  width: 100%;
  padding: 1rem 1.1rem;
  text-align: left;
  cursor: pointer;
}

.exercise-list button strong,
.exercise-list button span {
  display: block;
}

.exercise-list button strong {
  margin-bottom: 0.25rem;
  font-size: 1rem;
}

.exercise-list button span {
  color: var(--muted);
  line-height: 1.45;
}

.exercise-list button.active {
  border-color: rgba(18, 65, 112, 0.35);
  background: var(--accent-soft);
}

.exercise-panel {
  padding: 1.3rem;
}

.exercise-header {
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--line);
}

.exercise-header p {
  margin: 0.45rem 0 0;
  color: var(--muted);
}

.exercise-links {
  margin-top: 0.8rem;
}

.question-list {
  display: grid;
  gap: 1rem;
  margin-top: 1.1rem;
}

.question-card {
  padding: 1rem;
  border-radius: 20px;
  border: 1px solid var(--line);
  background: #fffcf6;
}

.question-number {
  display: inline-block;
  margin-bottom: 0.6rem;
  padding: 0.25rem 0.55rem;
  border-radius: 999px;
  background: var(--surface-strong);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.question-card p {
  margin: 0;
}

.question-body img {
  max-width: 100%;
  height: auto;
}

.question-body .figure-note {
  margin: 0.85rem 0 1rem;
  padding: 0.85rem 1rem;
  border-radius: 0.85rem;
  background: rgba(18, 65, 112, 0.06);
  color: rgba(18, 65, 112, 0.78);
  font-size: 0.98rem;
}

.answer-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1rem;
}

.answer-row input {
  flex: 1 1 240px;
  min-height: 46px;
  padding: 0.75rem 0.9rem;
  border-radius: 14px;
  border: 1px solid rgba(18, 65, 112, 0.2);
  background: white;
  font: inherit;
}

.answer-row button {
  min-height: 46px;
  padding: 0.75rem 1rem;
  border: 0;
  border-radius: 14px;
  background: var(--accent);
  color: white;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.feedback {
  display: none;
  margin-top: 0.85rem;
  padding: 0.9rem 1rem;
  border-radius: 16px;
  line-height: 1.65;
}

.feedback.is-visible {
  display: block;
}

.feedback-success {
  background: rgba(74, 146, 89, 0.12);
  border: 1px solid rgba(74, 146, 89, 0.22);
}

.feedback-error {
  background: rgba(201, 109, 51, 0.12);
  border: 1px solid rgba(201, 109, 51, 0.2);
}

.feedback p {
  margin: 0;
}

.question-footer {
  display: flex;
  justify-content: flex-end;
  margin-top: 0.95rem;
  padding-top: 0.8rem;
  border-top: 1px solid rgba(18, 65, 112, 0.1);
}

.question-backlink {
  font-size: 0.95rem;
  font-weight: 700;
}

.solution-details {
  margin-top: 0.85rem;
  border-top: 1px solid rgba(18, 65, 112, 0.12);
  padding-top: 0.75rem;
}

.solution-details summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--accent);
}

.solution-content {
  margin: 0.85rem 0 0;
  padding: 0.9rem;
  overflow-x: auto;
  white-space: normal;
  border-radius: 14px;
  background: rgba(18, 65, 112, 0.05);
  line-height: 1.7;
}

.solution-line {
  margin: 0 0 0.75rem;
}

.solution-line:last-child {
  margin-bottom: 0;
}

.solution-line-math {
  overflow-x: auto;
}

.solution-line-math mjx-container[display="true"] {
  margin: 0.2rem 0;
}

.solution-table-wrap {
  margin: 0.25rem 0 0.85rem;
  overflow-x: auto;
}

.solution-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.98rem;
  background: rgba(255, 255, 255, 0.72);
}

.solution-table th,
.solution-table td {
  padding: 0.55rem 0.7rem;
  border: 1px solid rgba(18, 65, 112, 0.14);
  text-align: left;
  vertical-align: top;
}

.solution-table th {
  background: rgba(18, 65, 112, 0.08);
  font-weight: 700;
}

.solution-content mjx-container {
  margin: 0 0.2rem;
}

.resource-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

@media (max-width: 980px) {
  .hero,
  .lecture-card-featured,
  .exercise-layout,
  .goal-grid,
  .resource-grid,
  .exercise-intro {
    grid-template-columns: 1fr;
  }

  .lecture-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .lecture-card-featured {
    grid-column: auto;
  }
}

@media (max-width: 720px) {
  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .topnav {
    justify-content: flex-start;
  }

  .lecture-grid {
    grid-template-columns: 1fr;
  }

  .hero-copy,
  .hero-panel,
  .exercise-panel,
  .goal-card,
  .resource-card,
  .exercise-note {
    padding: 1.15rem;
  }

  .answer-row {
    flex-direction: column;
    align-items: stretch;
  }
}